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JAMB Physics 2023 Paper

Question : 18

Total: 65

A 200 kg load is raised using a 110 m long lever as shown in the diagram above. The load is 10m from the pivot P. If the efficiency of the the lever is 80%, find the effort E required to lift the load.

[Take g = 10ms-2]

Validate

Solution:

ε= 80%, L=200× 10 = 2000N, $d_L$ =10m

$d_E$ = 110-10 = 100m, E=?

ε =

\frac{\text{work done on the load}}{\text{work done by the effort}}

× 100%

⇒ work done on load = 2000 ×10 =20,000 j

⇒ work done by effort = E × 100 = 100E

⇒ 80 =

\frac{20,000}{100E}

× 100%

⇒ 80 =

\frac{20,000}{E}

⇒ E =

\frac{20,000}{80}

⇒ E = 250N

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